gh-89973: Fix re.error in the fnmatch module. (GH-93072)

Character ranges with upper bound less that lower bound (e.g. [c-a])
are now interpreted as empty ranges, for compatibility with other glob
pattern implementations. Previously it was re.error.
(cherry picked from commit 0902c3d8)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>